Use notification display service to collect persistent notifications.

chrome/browser/notifications/notification_test_util.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_TEST_UTIL_H_
 #define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_TEST_UTIL_H_
 
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 32 matching lines @@
   // Returns the number of currently active notifications.
   unsigned int GetNotificationCount() const;
 
   // Returns a reference to the notification at index |index|.
   const Notification& GetNotificationAt(unsigned int index) const;
 
   // Sets a one-shot callback that will be invoked when a notification has been
   // added to the Notification UI manager. Will be invoked on the UI thread.
   void SetNotificationAddedCallback(const base::Closure& callback);
 
+  // Emulates clearing a notification from the notification center
+  // without running any of the delegates. This is often possible
+  // from native notification centers.

[Peter Beverloo, 2016/12/02 13:43:34]

s/This is...notification/centers/ -->

This may happen when native notification centers don't inform us about closed
notifications, for example as a result of a system reboot.

[Miguel Garcia, 2016/12/06 12:01:18]

Done.

+  bool ClearNotificationById(const std::string& delegate_id,

[Peter Beverloo, 2016/12/02 13:43:34]

nit: what about "SilentDismissById" to further distinguish from CancelById? I'd
love the name to reflect how it's different from regular cancellation.

[Miguel Garcia, 2016/12/06 12:01:18]

Done.

+                             ProfileID profile_id);
+
   // NotificationUIManager implementation.
   void Add(const Notification& notification, Profile* profile) override;
   bool Update(const Notification& notification, Profile* profile) override;
   const Notification* FindById(const std::string& delegate_id,
                                ProfileID profile_id) const override;
   bool CancelById(const std::string& delegate_id,
                   ProfileID profile_id) override;
   std::set<std::string> GetAllIdsByProfileAndSourceOrigin(
       ProfileID profile_id,
       const GURL& source) override;
@@ skipping 20 matching lines @@
   void Wait();
 
  private:
   Browser* browser_;
   bool desired_state_;
 
   DISALLOW_COPY_AND_ASSIGN(FullscreenStateWaiter);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_TEST_UTIL_H_